In crown and bridge prosthodontics, metal copings are conventionally used to provide the essential structural strength and rigidity necessary for a dental restoration to resist the forces of mastication. In a ceramic-to-metal dental restoration, the metal coping represents the retaining member which forms the understructure of the restoration in the preparation of a single or multiple unit bridge. A bridge is used to replace at least one missing tooth and is supported by one or more natural teeth. The bridge includes a pontic which fills the edentulous space represented by the missing tooth and a connector which serves to connect the pontic to a retaining member formed on an abutment tooth adjacent the pontic. The bridge may be a single unit bridge involving the preparation of one or two retaining members or a multiple unit bridge. The pontic is formed from a model of the missing tooth and is typically of cast metal. The connector is typically a soldered joint extending between the cast metal structure and the coping.
For purposes of the present invention any conventional method may be used to form the dental metal coping and any conventional method may be used to form the metal structure although a cast structure is preferred. The dental metal composition of the present invention forms a soldered connection between a dental coping composed of precious metals and a metal structure composed entirely or substantially of precious metals.
The soldered joint formed between the metal coping and metal structure should result in a strong rigid prosthetic structure without voids or gaps which would otherwise provide space for the growth of bacteria. Moreover, the soldering operation should not result in excessive shrinkage of the metal composition during heat treatment to preserve the physical and spatial relationship between the coping and the cast metal structure that existed before heat treatment and without causing oxidation.